Unit 2: Molecules

Question 1

What are the SI Units Prefixes?

Answer 1

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Question 2

Explain why carbon is the most suited for being the backbone of everything

Answer 2

Carbon:
- Since it has 4 valence electrons, It can form 4 single bonds and is thus suited for being the backbone due to its stability
- It allows carbs, lipids, proteins, and nucleic acids to form

Question 3

What is a monomer and polymer + in the context of carbohydrates?

Answer 3

Monomer:
- Molecules that join to other similar molecules to form a polymer OR one unit of something
EX: DNA’s monomers are nucleotides + Polymer = DNA
Carbohydrates:
- Their monomers are monosaccharides + polymer = carbs

Question 4

How are polypeptides formed?

Answer 4

Process:
- Polypeptides are made via condensation reactions which release a water molecule
- The OH/hydroxyl group is from both of the monosaccharide leaves. Leaving the molecule w one oxygen between them
- Bonds are usually formed between 1 and 4 prime carbon of diff. monosaccharides

Question 5

What is a monosaccharide

Answer 5

Monosaccharides:
- Defined as a single sugar molecule
- Atoms C,H,O are always in a 1:2:1 ratio EX: C6H12O6
- hydrogen to oxygen ratio is 2:1

Question 6

Carbohydrates are also broken down in digestion. What is the process?

Answer 6

Carbs:
- are broken via hydrolysis reactions
- Are defined by an addition of water to split apart the bond of a large molecule

Question 7

How are carbohydrates classified?

Answer 7

Classification:
- is classified based on the # of sugar molecules
- one sugar are called monosaccharide, two are disaccharides, and many are polysaccharides + poly are the energy for organisms

Question 8

Define hexose sugars and pentose sugars

Answer 8

Hexose:
- are monosaccharides with 6 carbon
EX: Glucose, galactose, fructose
Pentose:
- monosaccharide w 5 carbons
EX: deoxyribose and ribose

Question 9

What are alpha and beta glucose and its differences

Answer 9

Glucose:
- are types of glucose and hexose sugars
- alpha: at the one prime carbon, the hydroxyl group is pointed up
-Beta: at the one prime carbon, the hydroxyl group is going down

Question 10

Outline 3 properties of glucosej

Answer 10

Glucose:
1. is Soluble in water because it’s polar and can be dissolved in a polar solvent such as water
2. can be easily transported EX: in the bloodstream
3. relatively stable compound and doesn’t degrade as its being transported cause strong cov bonds 4. Yields a great amount of energy when the covalent bonds break

Question 11

What are the energy sources in plants and it’s structure

Answer 11

Starch:
- Starch is made of amylose amylopectin
- Amylose: long chains of alpha glucose molecules
- Amylopectin: long chains of alpha glucose + branching of alpha glucose
- Starch is not soluble in water due to the size which allows for compact storage of starch grains w out affecting osmotic pressure
- After 20 glucose units, amylopectin has a branch
- They are bonded w glycosidic bonds
- are compact due to branching and coiling
Note: Starch is made of glucose molecules

Question 12

What is the energy source for animals:?

Answer 12

Glycogen:
- is defined as a polysaccharide for short-term energy
- has cov bonds between 1 + 4 carbon and has branches of alpha glucose bonding to 6 prime carbon
- Its insoluble, and compact due to branches and coiling
Note: Glycogen is made of glucose molecules

Question 13

What is the polysaccharide found in the cell wall of plants?

Answer 13

Cell wall:
- cellulose has long chains of beta glucose molecules which are unbranched
- molecules bonded between 1 + 4 carbon
- every second beta glucose molecule is flipped resulting in a straight chain
- Cellulose forms groups called microfibrils held together by hydrogen bonds
- Microfibrils have high tensile strength to maintain the structural integrity of cell wall

Question 14

What are the different types of fatty acids and their composition?

Answer 14

Fatty acids:
- Contain a carboxyl group (-COOH) and a methyl group (-CH3)
- can be saturated: only contains single bonds between hydrocarbon chain
- can be unsaturated which means they have double bonds that are bent and are called kinks
- Amongst unsaturated, it can be monounsaturated or polyunsaturated meaning one or many double bonds

Question 15

How does carbohydrate assist with membrane proteins ?

Answer 15

Mem proteins:
- glycoproteins have a carbohydrate chain
- the carb has a specific shape that can act as an antigen: the molecule that binds to a receptor on a cell surface for cell to cell communication (ID card)

Question 16

Outline the roles of glycoproteins

Answer 16

Glycoproteins:
- cell to cell adhesion: interact with other glycoproteins to form tissue
- receptors: when hormones bind = changes metabolism in cell
- cell-cell communication: neurotransmitters bind to glycoproteins
- immune response: act as markers on cells allowing the immune system to distinguish outside cells
- act as an antigen which simulates an immune response = production of antibodies to remove pathogens

Question 17

Outline the differences in fats and oils

Answer 17

Fats:
- fats are triglycerides which are solid at room temperature
- they have a higher MP and are usually saturated
- used by animals
Oils:
- oils are triglycerides that are liquid at room temperature w a lower MP
- fatty acids are unsaturated because the kinks mean they are more spread out so they turn liquid
- Oils are used by plants and fish

Question 18

Outline the composition of triglycerides and phospholipids

Answer 18

Triglycerides:
- made of one glycerol molecule (a sugar) and 3 fatty acids

Phospholipids:
- made of one glycerol molecule + 2 fatty acids + one phosphate

• both are formed via condensation reactions

Question 19

Explain how triglycerides are good insulators

Answer 19

• triglycerides are good insulators cause they have a low thermal conductivity

Question 20

Outline the composition of steroids + whether they can diffuse across cell mem + examples

Answer 20

Steroids:
- they are lipids with 4 carbon rings +. a hydrocarbon chain
- They can diffuse through the cell mem cause they dissolve in fatty acid tail
EX: Oestradiol and testosterone

Question 21

Outline the properties of water + give some examples of whr water can be found

Answer 21

Water:
- is polar, covalent, w weak charges at poles
- is dense as a liquid than a solid EX: ice floats in water
- can bond with 4 other water molecules

Examples:
- water makes up the cyto and is also found between cells as interstitail fluid because metabolic processes work best in an aqueous environment

Question 22

What is electronegativity + explain why water is polar

Answer 22

Electronegativity:
- the strength of attraction between an atom and its valence electrons

Water:
- oxygen has a more positive nucleus than hydrogen atoms and has greater attraction for the elctrons
- So electrons are shared unequally
- the hydrogen bonds of water are weak

Question 23

Explain why water is a good solvent

Answer 23

Water:
- it dissolves stuff well EX: anyt polar will dissolve
- water forms hydrogen bonds with anything polar and pulls it apart

Question 24

What is the xylem in plants

Answer 24

Xylem:
- a thin narrow tube that transports water and the nutrients in the water from the roots of the plant to the leaves
- This is due to capillary action: the ability of water to flow against gravity in a narrow space + the co/adhesion of water
- water sticks to the plant and also to other water molecules

Question 25

Define cohesion, adhesion, and surface tension

Answer 25

Cohesion:
- attraction between the same kind of molecules

Adhesion:
- Attraction between different kinds of molecules

Surface tension:
- property allowing liquid to resist external forces

Question 26

Define buoyancy, viscosity, thermal conductivity, and specific heat capacity with examples in nature

Answer 26

Physical properties of water:

Buoyancy:
- defined as the upward force exerted by a fluid on something in the fluid
- since liquid water is less dense than air, aquatic animals have more buoyancy in water and float easier
- animal fat gives the animal more buoyancy

Viscosity:
- defined as a measure of a fluid’s resistance to flow
- Since water has a higher viscosity than air, many animals have a streamlined body to move more smoothly through the water

Thermal conductivity:
- the rate at which heat passes through the material and will vary based on the collision of particles
- since water has a higher TC than air, animals in water lose heat faster
- animals have adapted to the rapid heat loss in water such as no dorsal fin

Specific heat capacity:
- is defined as the energy required to raise the temp of 1g of a substance by 1 Celsius
- water has a high heat cap of 4.186 j/g Celsius cause it has lots of hydrogen bonds to break
- animal cells are resistant to temp change so it maintain body temp
- metals can change temp quickly causing low heat cap cause they’re better conductors
- large bodies of water have high heat caps which is ideal for organisms that thrive in a range of temp

Question 27

Discuss why ice was not present during pre-biotic earth + how water came to earth

Answer 27

Water:
- water as ice was not present because the temp was too high + any gas water were moved by solar winds
- water formed outside of solar system due to low temp
- earth’s water came from asteroids or carbonaceous chondrites from the “Late Heavy Bombardment”

Question 28

What is the Goldilocks zone

Answer 28

Zone:
- planets are in a goldilocks zone where their orbit around stars allows for liquid water
- not too far from the sun and not too close
- earth’s temp is suitable for water cycle and for life

Question 29

Describe the composition of DNA and RNA + how does nucleotides form

Answer 29

Comp:
- made of a deoxyribose (sugar) + nitrogenous bases and a phosphate group
- same for RNA except the sugar is ribose
- These are called nucleotides which are formed via condensation reactions

Question 30

Outline differences between RNA and DNA

Answer 30

RNA:
- Single Stranded
- Has AUCG bases (AU + CG)
- has ribose sugar
- has an extra oxygen off 3 prime carbon
- relatively shorter

DNA:
- double-stranded or double helix
- is anti-parallel
- has ATCG bases (CG + AT)

Question 31

What is the composition of a nucleotide + the comp of pentose sugars

Answer 31

Nucleotide:
- Is defined as an organic molecule or pentose sugar, nitrogenous bases, and a phosphate group
- pentose sugars have 5 carbon called primes
- the fifth carbon is not on the molecule but instead bonded to a phosphate group.
- oxygen takes the last spot

Question 32

Define transcrption and translation

Answer 32

Transcription:
- DNA code is transcribed to mRNA code
- in nucleus

Translation:
- mRNA code is translated by ribosomes into a polypeptide sequence
- in ribosomes

Question 33

How many chromosomes does human usually have

Answer 33

Chromo:
- 23 pairs

Question 34

Define genes

Answer 34

sequences of nitrogenous bases which is a code for specific protein and determines amino acid sequence

Question 35

What is a codon

Answer 35

3 nitrogenous bases

Question 36

What are purines and pyrimidines

Answer 36

Purines:
- bases w 2-ringed structure EX: A and G

Pyrimidines:
- bases w 1 ring structure EX: U, T, and C

• pyrimidines bond with purines

Question 37

What is the tetranucleotide hypothesis and how was it debunked

Answer 37

Tetranucleotide Hypothesis:
- hypothesis that DNA had 4 strands and the DNA sequence is always TACG
a
- this was disproved by looking at the % of bases
- since the % of bases within the sample is diff, then it can’t always be TACG
- the conc of A and T are relatively equal + vice versa

Question 38

What is Chargaff’s rule

Answer 38

Chargaff:
- % of A = T and C=G are the same
- A bonds with T and creates 2 hydrogen bonds
- C and G bonds and creates 3 hydrogen bonds

Question 39

Describe the discovery of DNA

Answer 39

DIscovery:
- Watson and crick figured out the bases unions
- Rosalind Franklin generated DNA crystal and shot x rays through which produced a double helix

Question 40

What are nucleosomes

Answer 40

Nucleosome:
- is defined as negatively charge DNA wrapped twice around a core of 8 histones proteins + another linker histone protein to hold nucleosome tgt

Question 41

Explain the Hershey-Chase experiment

Answer 41

Experiment:
- The purpose of this experiment is to find out whether protein or DNA was the genetic information
- They let bacteriophages (which are viruses that infect bacteria with their genetic info) infect e coli
- This particular bacteriophage had a DNA core and a protein coat
- They labelled one w radioactive phosphorus and one w radioactive Sulfer because DNA contains phosphors and vice-versa
- The bacteriophage infected the bacteria
- They put the bacteria into a centrifuge to separate the heavy bacteria to come as a pellet
- fhey checked if it had radioactivity and found it in the dna sample or phosphorus radioactive
- This revealed that the bacteriophage injected DNA inside thus DNA must be the genetic information.
Note: the substance in the centrifuge that isn’t the pellet is called the supernatant

Question 42

Outline the composition of an amino acid

Answer 42

Amino acid:
- its made of an amine group, a central carbon or alpha carbon, and a carboxyl group + a side chain

Question 43

What is the importance of the R side chain

Answer 43

R Side Chain:
- R side chain determines the chemical characteristics of amino acids of an assembled polypeptide
- can be categorized as hydrophilic or hydrophobic

Question 44

How many types of amino acids are there

Answer 44

20 and all living organims share it

Question 45

How do polypeptides form+ how are they bonded + How are they classified

Answer 45

Form:
- Amino acids undergo condensation reactions to form polypeptides in the ribosome during translation
- they are bonded with peptide bonds which is a type of covalent bond

Classified:
- 1 = peptide, 2 = dipeptide, 20 = Oligopeptide, 20+ = polypeptide or a protein

Question 46

What is the difference between essential and nonessential amino acids + what are complete proteins

Answer 46

Essential:
- are amino acids that need to be obtained via diet
Non-essential:
- are amino acids that the body are able to synthesize

Complete:
- complete proteins contain 9 essential amino acids EX: meat

Question 47

Define denaturation + causes of denaturation

Answer 47

Denaturation:
- is defined as a conformational change in the shape of a molecule such as protein that results in loss of function
- when heated, the molecules vibrate a lot thus causing for the hydrogen bonds to break and ionic bonds break

Causes:
- could be due to pH or temp change
- it breaks that hydrogen bonds

Question 48

Describe the primary structure in protein folding

Answer 48

Primary:
- the primary structure simply establishes the sequence of amino acids
- they are formed via condensation reactions and bonded w peptide bonds
- Theres always a free amine group and a carboxyl group at the end as well

Question 49

Describe the secondary structure

Answer 49

Secondary:
- the protein starts to fold
- its held tgt with hydrogen bonds between oxygen of carboxyl and the hydrogen of amino group
- they can either be folded into a alpha helix or a beta pletaed sheet

Question 50

Describe the tertiary structure

Answer 50

Tertiary:
- further folding of proteins due to the R-group interactions
- interactions include covalnet, ionic, and hydrogen bonds forming
- an example of cov bond are disulfide bridges between cysteine
- in this stage, the hydrophobic amino acids will be in the globular proteins while the hydrophilic will be on the outside

Question 51

Describe quaternary

Answer 51

Quaternary:
- different polypeptides come tgt and r group from diff polypeptides are keeping them tgt
- r group interactions are the same as tertiary

Question 52

What are conjugated proteins + Non conjugated proteins

Answer 52

Conjugated:
- a conjugated protein is a protein attached to a non-polypeptide group which is called a prosthetic group EX: hemoglobin

Non Conjugated:
- non-conjugated proteins are composed of only polypeptides EX: insulin

Question 53

Describe the structure of collagen and insulin + their uses

Answer 53

Collagen:
- is a fibrous protein composed of 3 polypeptide chains that are tightly coiled tgt in a triple helix structure
- main structural protein in connective tissue + provides structural support
- bonded together by disulfide bonds

Insulin:
- is a globular protein that is composed of two polypeptide chain that are inked by 2 disulfide bridges
- helps with blood regulation as it causes the liver to remove glucose from blood
- bonded together w hydrogen bonds
Note: we can use cryogenic microscopy to observe protein structure